The present invention relates to an electromagnetic inductor ingot mold for the continuous castings of blooms. The mold includes two relatively large and two relatively small rectangular, vertically disposed walls assembled to define a passage having an elongated rectangular section for the casting of a bloom. At least each of the two relatively large walls is formed by a water cooled box which cools the molten metal in the mold. Each cooling box includes a rectangular vertical wall which is parallel to the relatively large wall forming the mold and which is held away from the mold wall by means of braces formed of bars. The braces are arranged in rows and columns in a matrix arrangement. An electromagnetic inductor is housed in each of the cooling boxes and comprises a magnetic circuit having inductive windings connected to a power source so as to create a varying magnetic field.
With the increasing development of continuous casting, and the heretofore recognized success of electromagnetic rabbling, i.e., stirring, it is desireable to combine these two processes in the molding of liquid metal into ingot molds.
By putting molten metal into movement upon its introduction into an ingot mold through electromagnetic rabbling, the impurities in suspension in the liquid metal are removed from the zone at which solidification of the metal begins. These impurities can be recovered in the form of slag on the surface of the molten bath.
Electromagnetic rabbling in an ingot mold has been previously used with ingot molds for the continuous casting of billets. In these systems, an inductor which is capable of creating a rotating magnetic field is incorporated in a cooling box placed around a casting pipe.
In the case of ingot molds for continuous casting of blooms, however, a problem arises due to the fact that the casting well is formed by the fitted assembly of four vertical walls made up of separable cooling boxes. These boxes are closed and are not in fluid communication with one another. The two relatively large boxes forming the large faces of the bloom and the two relatively small boxes which are perpendicularly disposed with respect to the large boxes and in contact with the small faces of the bloom each form independent cooling volumes.
Furthermore, only the two relatively large boxes provide sufficient useful volume to house an electromagnetic inductor therein. Normally, one inductor is placed adjacent each large face of the ingot mold and a continuous field surrounding the mold cannot be created.
In addition to the difficulty presented by not having a continuous field around the mold a further problems is presented due to the small amount of space available in which to house the inductor. The braces or other similar devices which space the large internal and external vertical walls of the relatively large cooling boxes cut down on the amount of space available for an inductor.
One proposed solution to this problem is disclosed in French patent application 75.28439, filed Sept. 17, 1975 and published under number 2,324,395. In an ingot mold of the typed described previously, the braces are formed of bars and function as both the spacing pieces for the structure and polar pieces for the magnetic circuit of the inductor (FIGS. 5 and 6 of the patent application). This arrangement has the drawback of requiring massive poles which necessarily limit the value of the induction and, consequently, the effectiveness of the rabbling.
It is an object of the present invention to remedy this drawback by providing an inductor which is capable of being housed in existing ingot molds of the type in which the relatively large internal and external walls of the cooling boxes are held apart by braces formed of bars arranged in a matrix arrangement, and which is able to produce more effective rabbling.
To achieve this purpose, an ingot mold according to the present invention has an inductor which includes comb-shaped cores with slots parallel to either the horizontal or vertical directions. The core is subdivided, perpendicular to the direction of the slots, into individual magnetic circuits. The inductive winding of each circuit comprises two parallel groups of rectilinear active conductors housed in the slots of the core. The individual magnetic circuits and the groups of rectilinear active conductors of the inductive windings form a grid interlaced within the lines and columns of the matrix arrangement formed by the braces.
With this arrangement, it is possible to otain a magnetic field which varies vertically or horizontally, depending on whether the individual magnetic circuits are arranged vertically or horizontally, respectively, and whether the groups of rectilinear active conductors of the inductive windings are arranged respectively horizontally or vertically.
Ingot molds for continuous casting of blooms are known which comprise one or more electromagnetic inductors per cooling box, with each inductor having a magnetic circuit in the form of a comb with slots parallel to either the vertical or horizontal directions and with each winding comprising two groups of rectilinear active conductors housed in the slots of the magnetic circuit. Such arrangements are disclosed, for example, in French patent application No. 2,324,395, previously cited, (FIGS. 2 and 3) or French patent application published under No. 2,324,397 (FIG. 2). The teeth or polar pieces of the magnetic circuits described in these two French patent applications also serve as support pieces between the large vertical walls of the cooling boxes. However, such magnetic circuits cannot be housed in the cooling boxes of existing ingot molds of the type in which the support pieces are made up of a matrix arrangement of braces formed of bars.